How to insert an element into an array?

In Swift, methods append, insert(at:), or operators += are used to insert elements into an array.

1. append(_:): Adds a single element to the end of the array.

   var array = [1, 2, 3]
   array.append(4) // [1, 2, 3, 4]
   

2. append(contentsOf:): Adds the contents of another sequence (e.g., another array) to the end of the current array.

   var array = [1, 2, 3]
   let newElements = [4, 5]
   array.append(contentsOf: newElements) // [1, 2, 3, 4, 5]
   

3. insert(_:at:): Inserts a single element at the specified index. Elements at and after this index are shifted to the right.

   var array = [1, 2, 3]
   array.insert(99, at: 1) // [1, 99, 2, 3]
   

4. insert(contentsOf:at:): Inserts the contents of another sequence at the specified index.

   var array = [1, 2, 3]
   let newElements = [99, 88]
   array.insert(contentsOf: newElements, at: 1) // [1, 99, 88, 2, 3]
   

5. Operator +=: Adds either a single element (if in square brackets) or elements of another sequence to the end of the array.

   var array = [1, 2, 3]
   array += [4] // [1, 2, 3, 4]
   array += [5, 6] // [1, 2, 3, 4, 5, 6]